David Cameron faced demands yesterday to hold an early referendum on Europe as a poll by a Tory peer showed Labour on course for victory at next year’s general election.

In an article for The Sunday Times (£), David Davis, a standard bearer of the Tory right, warned that Cameron’s policy position on the European Union lacks “both clarity and credibility”.

Former Conservative minister and shadow home secretary Credit: PA

He wrote: "We appear to be moving crab-like towards a referendum in 2017, without a clearly articulated set of strategic negotiating aims that might make it worthwhile to stay in the EU, or a clear vision of what we will do if the people decide they want to leave.

"We should start by bringing the referendum forward to 2016. The reform negotiation has barely got under way, precisely because the date is so distant [...] if we do not grasp this nettle, I can see the UKIP resurgence carrying all the way through to the general election".

Lord Ashcroft, former deputy chairman of the Conservative party Credit: James Edgar/PA Wire

A poll by former Conservative party deputy chairman Lord Ashcroft has found Labour could win "a comfortable majority" in the 2015 general election.

Lord Ashcroft polled more than 26,000 voters in 26 marginal constituencies that will be hotly contested battlegrounds between Labour and the Tories.

He said: "Across the battleground I found a 6.5% swing from the Conservatives to Labour – enough to topple 83 Tory MPs and give Ed Miliband a comfortable majority. But this is a snapshot, not a prediction."

He added: "The research also found that most voters in these seats are optimistic about the economy, and only three in ten would rather see Mr Miliband as Prime Minister than David Cameron. Half of voters say they may change their mind before the election – and there is still a year to go."

George Osborne has said he "respects" Ukip leader Nigel Farage and those who voted for his party at this week's local and European Parliament elections.

George Osborne urged the Tories to respond to the 'anger and anxiety' causing people to vote for Ukip. Credit: Wiktor Dabkowski/DPA/Press Association Images

Speaking on Radio 4's Today programme, the Chancellor said: "I respect anyone who wants to put forward about ideas about how this country should be run, I respect participants in the political debate, including Nigel Farage."

Mr Osborne also urged his Conservative colleagues to listen and respond to the "anger and anxiety" that have led people to vote for Ukip.

Six in ten people who voted Ukip in the European elections did so as a protest, according to polling from the influential Conservative, Lord Ashcroft.

Writing on the Conservative Home website, the peer said his survey of 4,000 voters found that 60% of Ukip voters had said they were voicing anger at the party they usually vote for or registering a more general protest.

However 80% of Ukip voters also said they thought Nigel Farage's party had the best policies on Europe.

The results of Thursday's European Parliament vote will be revealed tomorrow.